Photoresist (PR) is widely used as mask patterns for form layers in TFT technologies. There are two types photoresist, i.e. positive photoresist and negative photoresist. When exposed, the exposed areas of the positive photoresist are made to be solvable in a developer, and the unexposed areas are left as a pattern.
The concentration of a photoresist in a stripping liquid (also be called as stripper) is usually measured by UV-VIS (Ultraviolet and Visible Spectrophotometer). In this method, the absorbance are read directly and stored in a database to measure the concentration of a photoresist in a stripping liquid. In this method, the operation is complicated and it is not suitable to put into practice.